THE .. Holmes – Allen .. Automatic Non-fouling TROLLEY HEAD

Progress, Volume I, Issue 6, 2 April 1906, Page 133

THE .. Holmes - Allen .. Automatic Non-fouling TROLLEY HEAD

Messrs. Holmes and Allen have solved the important problem of producing a trolley head for electrical 'tramways which will not foul the overhead gear, and which, in the opinion of many Tramway Engineers to whom it has been shown, will ere long become universal and, m fact, the standard head for use on all overhead systems. An account of how the inventors, Messrs. Holmes & Allen, attacked and finally crossed the pons asinoYiim of trolley-head design will be of interest to Progress readers. It appears about six months ago, as the result of a chance conversation, the inventors, who are engineers, decided to go into the matter and see if something could not be done to mitigate the evil existing with the present types of trolley head. On exchanging ideas, it transpired that each had been cogitating on similar lines The first problem the inventors took m hand was that fascinating one which necessitated some form of retrieving device. They set out on the cars all over the system to find out the peculiarities of the overhead construction. Havirrg got all necessary information they went to work to make patterns lor a trolley head possessing a slight lifting motion which would operate as soon as the wheel left the wire. This was necessary to close a local electric circuit and set the retracting gear in motion. The design for the retrieving device was finished, and was said to have been ahead of any at present on the market Sfill the principle of attaching anything more to the cars was distasteful, and they did not rest contented. Then the germ of the idea embodied m the present head was conceived. The happy thought struck them that it would be better to make the lifting motion automatically guard the head from fouling in the event of the wheel leaving the wire. After working every night for months, without intermission, at various forms, they evolved the present apparatus, which is so complete that it appears unnecessary to seek for improvement. In shape and size the new head is similar to the head at present m use, it is only required to take off the old type and install the new — a work of a few moments. A glance at the photographs will show the action of the head. Figure i shows the head m running position. As is well known the trolley pole is supported by a powerful spring within the standard, this presses the wheel against the trolley wire with a pressure of from 20 to 28 lbs. The trolley wheel is journalled within a jaw which is pivotally mounted on a bracket, this bracket is hung on the top pin which passes through the cheeks of the head and, by means of the slot is free to move

up and down for about f- of an inch. At the bottom of this bracket there is a pin which takes into slots in the cheeks of the head, see figure 2. A spring connects the top pin, which is fixed to the head, to the bottom pm, which is fixed to the bracket. Now it is clear that pressure on the

wheel will extend the spring and force the bottom pin into the bottom slot, thus, so long as the wheel keeps the wire, maintaining the wheel m a vertical position. If, however, the spring connecting the pins is free to contract, thus withdrawing the bottom pin from the slot — the centre of gravity being located behind the pivotal pomt — the whole bracket is free to swing downwards, describing an arc similar to the quadrant on the cheeks, and taking up the position shown in figure 2. This action automatically rings the motor-man's or conductor's bell, thus giving a timely signal. The mere fact of pulling on the rope to bring the pole below the wire resets the head. In case the motor-

man is unable to pull up before some of the overhead suspension wires or " Vs " are encountered, the pole simply slides down the wire and passes freely underneath, a different result to that experienced at present, where it is almost a certainty that the head will catch, and an accident more or less serious take place. The above facts have been substantiated by practical trials of the severest description. Another advantage of the invention is that the wheel persistently remains on the wire, refusing to leave it, even when what is usually reckoned the maximum allowable speed at corners, etc., is passed. Briefly put, the constant upward pull of the spring, independent of that of the trolley arm, assists to retain the wheel m its place. Another feature of the spring is that the old noisy screech and hammer blows, which are a noticeable feature of all existing heads, are reduced to a minimum. With the old trolley head the hammer blow downwards is followed by an immediate return blow as the wheel lands again on the ear ; this fault is now largely mitigated, as the spring maintains the wheel against the wire and so saves the second blow The speculator and business man have not been asleep, and some of the offers made to the inventors would seem tempting indeed if it were not for the fact that the venture appears destined to revolutionise matters — offers have also been received from various Governments, Corporations, Tramway Companies, etc — and negotiations are at present on foot with capitalists anxious to acquire the rights for Europe and Africa. An offer to buy the rights for the whole of the world _ has been refused. On the 25th ult., at the instance of His Worship the Mayor of Wellington and the Tramway Engineer, Messrs. Holmes and Allen granted the * Corporation a week's trial of their device. We are informed that the trolley head has since been subjected to exceedingly hard usage, and it has satisfactorily negotiated the severest tests. In concluding our notice it should be mentioned that the inventors were both engaged on the construction of the Wellington Tramways, and that the practical knowledge of the system thereby gained has proved of inestimable value to them in their experiments with the device.